There is a growing need for networking within the home. This need is driven by two major factors, the increasing use of multiple data devices and the emergence of broadband services in the home.
Lately there has been an expansion in the number of homes in the USA with multiple personal computers. In addition, connectivity and networking capabilities have been added to appliances, such as refrigerators and microwave ovens. Furthermore, there is a trend toward enabling data connectivity among various multimedia (audio and video) appliances such as TV's, VCR's, receivers, and speakers. The term “data unit” as used herein denotes any device capable of generating and/or receiving data. The networking of data units enables the sharing of files and applications as well as the sharing of common peripheral devices, along with other benefits.
Another driving force behind the need for home connectivity products is the growth in the number of on-line households. As high-speed connections to information and broadband entertainment sources soar, there is a growing need to share and distribute this access among appliances within the house. These broadband services are supplied mainly by three types of service providers:
Telco's, via xDSL connections (currently ADSL, to be followed by VDSL).
CATV. Currently via Cable-Modem, to be followed by digital Set-Top-Box.
Wireless connections, such as Satellite, LMDS, WLL, and others.
Communication within a home can be classified into two types: wired and non-wired. These are covered below:
Wired Communication
Wired communication requires using at least two distinct electrical conductors. The wiring can be new wiring installed and dedicated for data communication within the home, such as installing structured wiring such as Category 5 type, used in Ethernet IEEE802 networks. However, the installation of a new wiring structure within a home is labor-intensive, complex, and expensive. Alternatively, existing home wiring, which was previously installed for a specific purpose, can be used for data communication without substantially affecting or degrading the original service. Existing wiring includes telephone wiring, power line wiring, and cable TV wiring. These are reviewed below.
For all wired configurations, the present invention relies upon electrically-conducting lines which may be pre-existing within a building, which have at least two distinct electrical conductors, and which are capable of transporting data communication signals. Furthermore, the present invention relies upon suitable outlets, to which the electrically-conducting lines are coupled, and which are capable of connecting to external devices.
Telephone Wiring
In-home telephone service usually employs two or four wires, and is accessed via telephone outlets into which the telephone sets are connected.
FIG. 1 shows the wiring configuration of a prior-art telephone system 10 for a residence or other building, wired with a telephone line 5. Residence telephone line 5 consists of single wire pair which connects to a junction-box 16, which in turn connects to a Public Switched Telephone Network (PSTN) 18 via a cable 17, terminating in a public switch 19, which establishes and enables telephony from one telephone to another. The term “analog telephony” as used herein denotes traditional analog low-frequency audio voice signals typically under 3 KHz, sometimes referred to as “POTS” (“Plain Old Telephone Service”), whereas the term “telephony” in general denotes any kind of telephone service, including digital service such as Integrated Services Digital Network (ISDN). The term “high-frequency” as used herein denotes any frequency substantially above such analog telephony audio frequencies, such as that used for data. ISDN typically uses frequencies not exceeding 100 KHz (typically the energy is concentrated around 40 Khz). The term “telephone line” as used herein denotes electrically-conducting lines which are intended primarily for the carrying and distribution of analog telephony, and includes, but is not limited to, such electrically-conducting lines which may be pre-existing within a building and which may currently provide analog telephony service. The term “telephone device” as used herein denotes, without limitation, any apparatus for telephony (including both analog telephony and ISDN), as well as any device using telephony signals, such as fax, voice-modem, and so forth.
Junction box 16 is used to separate the in-home circuitry from the PSTN and is used as a test facility for troubleshooting as well as for wiring new in the home. A plurality of telephones 13a and 13b connects to telephone lines 5 via a plurality of telephone outlets 11a, 11b, 11c, and 11d. Each outlet has a connector (often referred to as a “jack”), denoted in FIG. 1 as 12a, 12b, 12c, and 12d, respectively. In North-America, RJ-11 is commonly used. Each outlet may be connected to a telephone unit via a connector (often referred to as a “plug”), denoted in FIG. 1 (for the two telephone units 13a and 13b illustrated) as 14a and 14b, respectively. It is also important to note that lines 5a, 5b, 5c, 5d, and 5e are electrically the same paired conductors.
While network 10 exhibits serial or daisy-chained topology wherein the wiring is serialized from an outlet the next one only, other topologies such as star, tree or any arbitrary topology may also exist. However, the telephone wiring system within a residence is always composed of wired media: two or four copper wires, and several outlets which provides direct access for connecting to these wires.
There is a requirement for simultaneously using the existing telephone infrastructure for both telephone and data networking. In this way, the task of establishing a new local area network in a home or other building is simplified, because there would be no additional wires to install. U.S. Pat. No. 4,766,402 to Crane (hereinafter referred to as “Crane”) teaches a way to form LAN over two-wire telephone lines, but without the telephone service.
As another example, relevant prior-art in this field is disclosed in U.S. Pat. No. 5,896,443 to Dichter (hereinafter referred to as “Dichter”). Dichter suggests a method and apparatus for applying frequency domain/division multiplexing (FDM) technique for residential telephone wiring, enabling simultaneously carrying telephone and data communication signals. The bandwidth enabled by the wiring is split into a low-frequency band capable of carrying an analog telephony signal and a high-frequency band capable of carrying data communication signals. In such mechanism, the telephone service is not affected, while data communication capability is provided over existing telephone wiring within a home.
The concept of frequency domain/division multiplexing (FDM) is well-known in the art, and provides means of splitting the bandwidth carried by a wire into a low-frequency band capable of carrying an analog telephony signal and a high-frequency band capable of carrying data communication or other signals. Such a mechanism is described, for example, in U.S. Pat. No. 4,785,448 to Reichert et al. (hereinafter referred to as “Reichert”). Also widely used are xDSL systems, primarily Asymmetric Digital Subscriber Loop (ADSL) systems.
The Dichter network is illustrated in FIG. 2, which shows a network 20 serving both telephones and providing a local area network of data units. Data Terminal Equipment (DTE) units 24a, 24b, and 24c are connected to the local area network via Data Communication Equipment (DCE) units 23a, 23b, and 23c, respectively. Examples of Data Communication Equipment include modems, line drivers, line receivers, and transceivers (the term “transceiver” herein denotes a combined transmitter and receiver). DCE units 23a, 23b, and 23c are respectively connected to high pass filters (HPF) 22a, 22b, and 22c. The HPF's allow the DCE units access to the high-frequency band carried by telephone-line 5. In a first embodiment (not shown in FIG. 2), telephones 13a, 13b, and 13c are directly connected to telephone line 5 via connectors 14a, 14b, and 14c, respectively. However, in order to avoid interference to the data network caused by the telephones, in a second embodiment (shown in FIG. 2) low pass filters (LPF's) 21a, 21b, and 21c are added to telephones 13a, 13b, and 13c from telephone line 5. Furthermore, a low pass filter is also connected to Junction Box 16, in order to filter noises induced from or to the PSTN wiring 17. It is important to note that lines 5a, 5b, 5c, 5d, and 5e are electrically the same paired conductors.
Additional prior-art patents in this field can be found under US Class 379/093.08, which relates to carrying data over telephone wiring without any modifications made to the telephone wiring (e.g. wires and outlets). U.S. Pat. No. 5,841,360 and U.S. patent application Ser. Nos. 09/123,486 and 09/357,379 to the present inventor are the first to suggest modifying the telephone wiring, by means of splitting the wiring into distinct segments, each of which connects two telephone outlets. In this way, the network is modified from ‘bus’ topology into multiple ‘point-to-point’ segments, enabling superior communication characteristics.
Part of such a network 30 is shown in FIG. 3, describing outlets 31a and 31b, substituting outlets 11 of FIGS. 1 and 2. The telephone wiring 5 is split into distinct segments 5a, 5b and 5c. Low-Pass Filter (LPF) and High-Pass Filters (HPF) are coupled to each wire segment end, in order to split between the telephony and the data signals. As shown in FIG. 3, LPF's 21b and 21c are attached to each end of wiring segment 5b. The LPF's are designed to allow passing of the telephony signals, and are connected together thus offering a continuous path for the telephony signals. Access to the telephony signals is made via connectors 12a and 12b in the outlets, into which telephone devices 13a and 13b are connected via connectors 14a and 14b respectively. Thus, the telephony service is fully retained. The data signals, carried in the high part of the spectrum, are accessed via HPF's 26a and 22b, coupled to each end of the telephone wire segment 5b. HPF's 22a and 26b are connected to the ends of the wire segments 5a and 5c respectively. Each HPF is connected to a modem 23 and 27, which transmit and receive data signals over the telephone wiring. Modems 23a, 27a, 23b, and 27b are connected to HPF's 22a, 26a, 22b and 26b respectively. Data units 24a and 24b are connected to the outlets 31a and 31b respectively, via a connector (not shown in the Figure) in the outlet. The data units are coupled via DTE interface in the outlet. Outlets 31a and 31b comprise DTE interfaces 29a and 29b respectively. The three data streams in each outlet, two from each modem and one from the DTE, are handled by an adapter 28a and an adapter 28b, which serve outlets 31a and 31b, respectively. While FIG. 3 describes an embodiment wherein all the components for the relevant functions are housed within the outlet, other embodiments are also possible, wherein only some of the components for these functions are contained within the outlet.
Power Lines
It is possible to transmit data over wiring used for distribution of electrical power within the home, which is normally at a frequency of 50 or 60 Hz. Access to the power is available via power outlets distributed around the house. Such wiring consists of two wires (phase and neutral) or three wires (phase, neutral, and ground).
FDM techniques, as well as others, are used for enabling data communication over power lines. Many prior-art patents in this field can be found in US Class 340/310.
Cable Television Lines
It is also possible to transmit data over wiring used for the distribution of television signals within the home. Such wiring usually is coaxial cable.
Both power line and cable television wiring systems resemble the telephone line structure described in FIG. 1. The wiring system is based on conductors, usually located in the walls, and access to these wires is obtained via dedicated outlets, each housing a connector connected directly to the wires. Common to all these systems, is the fact that the wiring was installed for a dedicated purpose (telephone, power, or cable TV signal distribution). Wherever one of these existing wiring systems is used for carrying data, it is desirable that the original service (telephony, power, or television signal distribution) be unaffected. Dedicated modems are used for carrying data over the media concurrently with the original service.
When using existing wiring, specific wired modems are normally required for communicating over the electrically-conducting lines, and access to the electrically-conducting lines is provided via the relevant outlets. Using electrically-conducting lines as the communication media allows for high bandwidth, and provides robust and cost-effective communication. In addition, communication over large distances is possible, which in most cases enables coverage of the whole house, thereby guaranteeing communication from any outlet to another within the house.
Such networks, however, require data units to be connected to the outlets, usually by means of a cable from the data unit to a suitable nearby outlet. This makes the connection complex and hard-to-use, requires the data unit to be in proximity to an appropriate outlet, and impairs mobility for some data units within the house.
Non-Wired Communication
Non-wired solutions for in-home data networking use waves propagated without an electrically-conducting medium. Three main techniques are commonly used:
Radio Frequency (RF). Transmission of data between data units can be accomplished with radio frequency electromagnetic signals. As an example, IEEE802.11 can be used.
Light. Transmission of data between data units can be accomplished with light in the visible or non-visible spectrum. Currently, the most popular is infrared (IR) based communication. Most such systems require ‘line-of-sight’ placement of the communicating data units.
Sound. Transmission of data between data units can be accomplished with sound waves, either in the audio spectrum (20-20,000 Hz), or inaudible spectrum (ultrasonic, above 20,000 Hz; or infrasonic, below 20 Hz).
It is noted that although light and radio waves are both electromagnetic phenomena, they occupy different parts of the electromagnetic spectrum and have significantly different characteristics for purposes of the present invention. Thus, light and radio waves are herein treated as distinct physical phenomena.
An example of a non-wired data network 40 is shown in FIG. 4. Two data units 41a and 41b are shown, into which non-wired transceivers 42a and 42b are respectively coupled. The non-wired transceivers 42a and 42b communicate over a space 43 without any electrically-conducting medium. If RF transmission is used, the transceivers are RF transceivers, and the communication over space 43 is based on the propagation of radio frequency electromagnetic waves. Similarly, in the case of light-based communication, transceivers 42a and 42b utilize light emitters (e.g. LEDs) and light detectors (e.g. photoelectric cell), and the communication over space 43 relies on the propagation of light. Likewise, in the case of sound-based communication over space 43, the transceivers use microphones and speakers, and the communication relies on the propagation of sound waves through the air in the space 43.
Since these solutions do not require any physical connection such as cable, they provide both ease-of-use and mobility. However, such non-wired solutions are effective over short distances only. Furthermore, most of the non-wired solutions cannot easily pass through walls and other such obstructions, owing to the attenuation to the signals. Hence, such techniques are suitable for communication within a single room, but are not suitable for communication between the rooms of a home or other building.
There is thus a widely recognized need for, and it would be highly advantageous to have, a means for implementing a data networking in-home between data units, wherein such data units can be networked within a home or other building, while providing mobility and ease of use. This goal is met by the present invention.